1. Field of the Invention
The present invention pertains to bore protectors and their use. In connection with subsea wells, a well head assembly is provided from which one or more casing strings are usually suspended. Additionally, a blow-out preventer is normally provided on the well head assembly above the casings. This blow-out preventer must be periodically tested to assure that it is working properly and, in particular, is usually tested at least before setting the first string of casing and after setting that string and each successive string. However, it is often necessary or at least advisable to test even more frequently.
In order to perform these tests, the bore of the well head must be sealed off, and adequate sealing requires a relatively smooth seal area on the well head bore against which a plug or the like can seal. However, such seal area can be marred or scored by apparatus extending into the well head during drilling and other operations due to the movements of such apparatus and/or the supporting platform caused by currents, wave action, etc. Accordingly, it is customary to employ a tubular or sleeve-like bore protector to cover and protect the seal area during such operations.
2. Description of the Prior Art
In the past, the tools used for running in and retrieving such bore protectors have been relatively complicated mechanically. This not only made the tools themselves expensive, but also made the running and retrieving process complicated and time consuming.
This problem has been further aggravated by the fact that it is impossible to seal the annulus between the well bore and the bore protector. Thus in most conventional systems, the bore protector has to be retrieved and re-set each time the blow-out preventer is tested.
Still another problem has resulted from the presence of "gumbo" in certain well formations which literally pumps the bore protector upwardly dislodging it from its seat in the well head.